Manufacture or treatment of artificial filaments



Sept. 28, 1937. H D Y S 2,094,005

MANUFACTURE OR TREATMENT OF ARTIFICIAL FILAMENTS Filed May 25, 1933 Patented Sept. 28, 1937 UNITED STATES PATENT OFFICE MANUFACTURE on TREATMENT OF ARTI- FICIAL FILAMENTS Henry Dreyfus, London, England Application May 1933, Serial No. 672,800 In Great Britain June 1, 1932 6 Claims.

This invention relates to improvement in the manufacture or treatment of artificial filaments, threads, ribbons, foils and the like and particularly to processes whereby their tensile strength may be improved. The present invention is a continuation in part of the invention described inby the use of swelling agents for the cellulose acetate, for example acetone, ethyl alcohol, formaldehyde or glycerine. U. S. application S. No. 378,684 filed 16th July, 1929 describes the stretching of filaments, threads or the like of 'cellulose acetate or other organic derivatives of cellulose, while they are travelling from one point to another, and in this case also, stretching is facilitated by the action of solvents or swelling agents for the cellulose derivative.

These specifications therefore, describe processes whereby the properties of artificial filaments, and particularly their tensile strength, may be improved by treating them with softening agents and stretching them.

I have now discovered that thesoftening of the artificial filaments and the like does not appear to increase uniformly with the time of treatment with the softening agent, but that after a certain period, which of course depends among other factors upon the type of material and upon the type, concentration and temperature of the softening' agent, a point is reached at which the material more or less suddenl y yields and a substantial stretch may be obtained. I have further discovered that by carrying out the stretching process in such a manner that the tension applied to the filaments or other products, in order to bring about the stretch, is" restricted or substantially restricted to the portion of the materials which has reached this state and is prevented from running-back to the portion of the materials in the earlier stages of their contact with the softening agent, considerable advantages may be obtained.

According to the present invention, therefore, artificial filaments, threads, yarns, ribbons, foils and the like are treated during the course of their travel from one. point to another with solvents, swelling agents or other softeningagents and subjected to tension so as to stretch them, at

force being applied to the materials only when they have reached a state in which they are relatively easily stretched.

While the process of the present invention is of particular value in relation to the .treatment of filaments, threads, ribbons, foils and the like made of or containing celluloseacetate and will therefore be described with particular reference thereto, yet it is alsoof value for the treatment of materials made from or containing other derivatives of cellulose, e. g. regenerated cellulose materials such as are obtained by the viscose, nitrocellulose and cuprammonium processes, and

more especially for materials containing organic derivatives of cellulose, such as cellulose esters or mixed esters, for example cellulose formate, cellulose propionate, cellulose butyrate and cellulose nitro-acetate, ethyl, propyl, benzyl andother simple or mixed cellulose ethers, and cellulose ether-esters, for example, ethyl cellulose acetate and oxy ethyl cellulose acetate.

The process of the present invention may be applied to the treatment of artificial filaments, foils and the like, either continuously with their production by wet or dry spinning processes, or as a separate operation, in which, for example, they are unwound from bobbins, spools or other suitable devices, are softened and stretched and are then re-wound. Since, however, as stated above, the invention is concerned with restricting or substantially restricting, the stretching tension to the softened portion of the materials it will be understood that it will be employed continuously with spinning processes only when the materials, after having been hardened or partially. hardened, are subsequently softened and stretched. Single filaments or yarns or bundles thereof may be treated, or the process may be applied to a number of threads simultaneously e. g. to a Warp, of threads from a suitable creel or beam.

Any suitable method of carrying out the invention may be employed, provided that thetension applied to produce the stretch is limited or substantially limited to the portions of the materials which have reached a swollen orsoftened condition. For example, the materials may be softened by passing them through a suitable bath containing a softening agent, either continuously with their production by wet 'or dry spinning processes, or from bobbina'pirns or other packages, and a mechanical device may be positionedin the bath in order to prevent the tension from running back to the portion of the materials which is in the earlier stages of its contact with the bath, and which is not in a sufficiently softened condition. Such device may comprise, for example, one or more rollers, either free or positively driven, around which the materials are wrapped, or one or more pairs of nip rollers, or guides or fork tensioning devices, such as are described, for example, in U. S. application S. No. 589,428 filed 28th January, 1932. If rotatable non-driven rollers are employed, they should not of course rotate so freely that restriction of the stretching tension is not effected. Such device may be positioned either wholly or partially in the bath or in some convenient position outside it. Again, two or more baths containing the softening agent may be employed and a mechanical device, such as that referred to above, may be positioned between any pair of baths, for example between the first two baths, so that the filaments or other materials are substantially softened in the first bath without being subjected to tension, or at least only to slight tension, and are then stretched in the second or subsequent baths, which may also contain softening agents, if desired in lower concentration.

While in general softening and stretching is preferably effected in a bath containing solvent or other softening agent, the invention is not of course limited thereto, and any other suitable means of bringing the materials into the condition required for stretching, and maintaining them in that condition during stretching, may be employed. Thus the materials may be sprayed with a solvent or passed through an atmosphere containing solvent, or such means may be employed only to maintain the yarn in a suitable condition for stretching after it has been previesses, or it may vary e. g. as regards type of agent,-

ously softened in a bath.

Either softening or stretching or both may be carried out in stages. Thus a thread or a number of threads may be carried round a series of rollers, and the first two may rotate at the same peripheral speed, while succeeding ones may rotate at successively increasing peripheral speeds so that an increasing degree of stretch is obtained. Softening without stretching may of course be effected between more than one pair of rollers.

The softening agent employed may be constant throughout the softening and stretching procconcentration or temperature during the processes. Thus, as described in U. S. application S. No. 638,776 filed 20th October, 1932, two or more softening treatments of different strengths may be employed. The softening baths may be of successively increasing or decreasing strengths, or baths of varying strengths which do not increase or decrease successively may be employed. Thus the strength of the bath in which stretching occurs may be less than that of the softening bath or baths, e. g. by reason of its lower temperature or lower concentration.

The weight of the yarn or other materials may also be employed according to the present invention in restricting the stretching tension to the softened portion of the materials. Thus a yarn proceeding from a bobbin or other package may pass downwards into a softening bath, under a roller or the like and then upwards and round a further roller from which it proceeds to a stretching device. Again, restriction of the stretch may be assisted by the use of a counter-current of liquid or gas, e. g. by causing the softening bath to flow in a direction opposite to that of the travel of the materials.

The softening agents used in connection with the present invention may be aqueous solutions of an inorganic substance, for example thiocyamates of the alkalies, ammonia and alkaline earths, or zinc chloride, or organic substances may be used, examples of which are acetic acid, formic acid, lactic acid, diacetone alcohol, acetone and the like; ethers and estersand ether-esters of olefine and polyolefine glycols, for example the monoand di-ethyl ethers of ethylene glycol, dioxane, and its homologues and substitution products and other cyclic ethers for instance methylene ethylene dioxide, dioxane dicarbinyl diacetate and alkylated dioxanes, the monomethyl and ethyl ethers of propylene glycol, the mono-methyl ether of diethylene glycol, the mono-esters of ethylene glycol, for example glycol monoacetate, and the ether-esters of ethylene glycol, for example methyl glycol monoacetate; phenols, formaldehyde, acetaldehyde, monoand di-acetins, dichlor-ethylene, ethylene chloride, methylene chloride and the like or mixtures of these or other substances. Most of the above organic substances may suitably be applied in aqueous solution. Other diluents may however be employed, as e. g. benzene, toluene and other hydrocarbons.

Examples of apparatus which may be employed according to the present invention are illustrated in the accompanying drawing, but it is to be clearly understood that they are given merely by way of example and that the invention is notlimited thereto in any manner:-

Figures 1 and 2 show a sectional elevation and a plan of an apparatus for the softening and stretching of foils and similar sheet-like materials. In this apparatus the foil or similar material 1, supplied for example from a roll, passes over the feed-roller 8 and under the guide 9 which is immersed in the softening bath contained in the vessel 6. A pair of nip-rollers l2 and I3 is positioned in the bath and the foil passes between these rollers, through the remainder of the bath, round the draw-rollers l0 and over the guide II to suitable washing, drying and winding apparatus. The nip rollers I2 and I3 prevent the stretching tension exerted by the draw-rollers ID from extending back to the material, between the feed roller 8 and the nip rollers, which is in an insufficiently softened state for stretching. The position of the nip rollers may of course be adjustable along the length of the bath to allow sufficient torque, or one or both may be positively driven. The softening agent is circulated through the bath by means of a draw-off pipe M, a pump I5 and a-feed pipe l6.

Figures 3 and 4 show a sectional elevation and a plan of an apparatus which may be employed in stretching a number of threads according to the present invention. The threads l8, supplied for example from a creel of bobbins, pass over a guide I9, under a feed roller 8 partially immersed in the softening bath contained in the vessel 6, and then through the softening bath to the draw-rollers l0 and guide I I, from which they pass to washing, drying and take-up apparatus.

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them being thus adjusted as required. Instead of being fixed the guides 20, 2| and 22, may if desired be rotatable but they should not of course be so freely mounted that the desired restriction of stretching tension is not effected. The softening liquid is circulated in a direction counter to that of thetravel of the materials by means of a draw-off pipe I4, a pump l5 and ai'eed pipeJB.

The following example is given of a suitable method of carrying out the invention but it is to be clearly understood that it does not limit the invention in any way A number of cellulose acetate threads proceeding, from a creel of bobbins, in parallel formation are passed over a'guide and under a feed roller partially immersed in a softening bath consisting of a to aqueous solution of dioxane, maintained at a temperature of 25 to 30 C. The threads proceed down the bath, which is of the order of to feet in length, and at a point about 30 feet along the bath they pass round a series of three guides, such as are illustrated for example in Figures 3 and 4 of the drawing. Thence they proceed to a draw-roller at the further end of the bath and round a guide to a washing, drying and winding apparatus. The peripheral speed of the draw-roller is about 20 to 30 metres per minute while that of the feed roller is 5 to 7 metres per minute so that a stretch of 400-500% is obtained. The angle of lap of the threads around the three guides is adjusted so that substantially no stretch occurs between the feed roller and these guides. In this manner materials having a substantially increased tenacity may be obtained.

What I claim and desire to secure by Letters Patent is:

1. In a process in which artificial filaments, threads, yarns, ribbons, foils and the like are rendered plastic by solvents or swelling agents for said material to a point where they may be readily stretched, the steps of stretching the materials during their travel from one point to another and mechanically restricting substantially all of the stretching tension to that portion of the materials during their travel from one point to another and mechanically restricting substantially all of the stretching tension to that portion of the materials which has attained and is in the readily stretchable condition.

3. In a process in which artificial filaments, threads, yarns, ribbons, foils and like products containing cellulose acetate are, rendered plastic by solvents or swellingagents for said cellulose acetate to a point where they may be readily stretched, the steps of stretching the materials during their travel from one point'to another and mechanically restricting substantially all of the stretching tension to that portion of the materials which has attained and is in the readily stretchable condition.

4. Process for improving the properties of fully formed artificial filaments, threads, yarns, ribbons, foils and like products containing organic derivatives of cellulose, which comprises rendering the products plastic by solvents or swelling agents for the organic derivative of cellulose to a point where. they may be readily stretched and subjecting them to a stretching operation in a plurality of stages during their travel from one point to another, the stretching tension being mechanically restricted to that portion of the products which has attained and is in the readily stretchable condition.

5. Process for improving the properties of fully formed artificial filaments, threads, yarns, ribbons, foils and like products containing organic derivatives of cellulose, which comprises rendering the products plastic by solvents or swelling agents for the organic derivative of cellulose to a point where they may be readily stretched and subjecting them to a stretching operation in a plurality of stages during their travel from one point to another, the stretching tension being mechanically restricted to that portion of the products which has attained and is in the readily stretchable condition, the stretching tension being substantially removed between at least two of the stages of stretching.

6. Process for improving the properties of artificial filaments, threads, yarns, ribbons and like products containing cellulose acetate, which comprises rendering a number of the products plastic by solvents or swelling agents for the cellulose acetate to a point where they may be readily stretched and stretching them during their travel from one point to another in warp formation, the stretching tension being mechanically restricted by means extending across the whole width of the warp to that portion of the products 'which has attained and is in the readily stretchable condition.

HENRY DREYFUS. 

